Pioneer A-90D (1987)
High-end stereo pre-main amplifier with built-in D/A converter, released in 1987 as part of Pioneer's EX series
Overview
The Pioneer A-90D is a stereo pre-main amplifier with a built-in D/A converter. Pioneer released it in 1987 as part of the EX series. It builds on the design foundation of the Pioneer A-717 and adds digital and analog integration to that core architecture. It has separate digital and analog power supplies, extensive shielding, and a honeycomb chassis structure meant to reduce noise and vibration.
Specifications
| Year of Production | 1987 |
| Rated Output (20 Hz to 20 kHz) | 180W + 180W (4 Ω, 0.005%) / 150W + 150W (6 Ω, 0.003%) / 120W + 120W (8 Ω, 0.003%) |
| Dynamic Power | 400W + 400W (2 Ω) / 280W + 280W (4 Ω) / 160W + 160W (8 Ω) |
| Harmonic Distortion Factor | 0.003% (8 Ω, 20 Hz to 20 kHz) |
| Input Sensitivity / Impedance | Phono MM: 2.5mV/50k Ω / Phono MC: 0.25mV/40 Ω / CD, Tuner, Line, Tape: 150mV/50k Ω |
| Maximum Allowable Input (1 kHz, 0.008%) | Phono MM: 200mV / Phono MC: 20mV |
| Output Level / Impedance | Tape Rec, Rec Out: 150mV/0.8k Ω |
| Frequency Characteristic | Phono MM: 20 Hz to 20 kHz ± 0.2 dB / Phono MC: 20 Hz to 20 kHz ± 0.3 dB / CD, Tuner: 1 Hz to 200 kHz +0, -3 dB |
| Tone Control (Volume -40dB) | Bass: 100 Hz, ± 8 dB / Treble: 10 kHz, ± 8 dB |
| Subsonic Filter | 7 Hz |
| Digital Inputs | Two optical inputs |
| Digital Outputs | One optical output |
| Original Price | ¥220,000 |
Design
The A-90D uses a honeycomb-shaped chassis formed by drawing for the frame and transformer, with punched honeycomb patterns on the bottom plate and bonnet case. The heat sink is extruded aluminum, also in a honeycomb shape. Five insulators support the internal components: four are resin-molded honeycomb and one is cast iron. The heavy transformer sits in a cast iron case. Digital and analog sections are physically separate, with dedicated power supplies and shielding for the digital circuits, including data demodulation, PLL, and digital filter. The signal path is kept short by direct construction. The unit has gold-plated input/output terminals, OFC grounding bus bars, copper-plated structural parts, and a newly developed large-capacity sealed capacitor that resists electromagnetic induction. The phono stage has a hybrid MC transformer, which turns off automatically when not in use. It also uses a non-switching TypeIII circuit to eliminate switching distortion. Each channel has its own D/A converter with a glitch-less IC, MSB error correction, and a high-jitter-suppression PLL. The digital filter oversamples by a factor of four and uses a high-performance IC for minimal in-band ripple (±0.0001 dB). It feeds a 5th-order Butterworth low-pass filter built with FDNR discrete circuits. A digital recording selector allows independent DAT recording, and a Source Direct Switch routes input sources straight to the main volume.
Product Family
The A-90D expands on the core design of the Pioneer A-717, enlarging its basic configuration with more digital integration and structural refinements.
Market
A used unit was listed for sale at 1,881.46 Canadian dollars with free shipping from Japan. One listing describes the unit as "testé fonctionnel" (tested functional).
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